VARIATION IN PEPLIS PORTULA L. 



By D. E. Allen 



Introduction. 



It has long been known that Peplis portula L. varies considerably in the length of 

 the outer calyx teeth. Although there is a general acceptance of the fact that this variation 

 has some geographical significance, little attempt has hitherto been made to discover 

 how far this assumption is justified. The present study was undertaken primarily to 

 plot the distribution of the variation in the British Isles, but in the course of the work a 

 number of interesting features have come to light and are discussed in this paper. 



The first notice of the variation in Britain was given by Dunn (1896), who, however, 

 made the surprising assertion that var. longidehtata Gay, a local race on the Continent, 

 appeared to be the only form occurring in this country. It is difficult to account for this 

 error, for Dunn is known to have been familiar with parts of Surrey and Warwickshire ; his 

 statement would have been understandable had his experience been confined, say, to the 

 Cornish Peninsula. The next mention was by Druce (1911) who, misunderstanding the 

 true nature of var. longidentata and misled by only finding specimens that did not display 

 the calyx character to an extreme degree, created a new variety dentata for the British 

 plants, which in his opinion formed a passage to the (supposedly) Mediterranean var. 

 longidentata. Druce's name was challenged by Thompson (1917), who rightly claimed 

 that perfectly good examples of var. longidentata were to be found in Britain and also 

 questioned the value of giving varietal names to " passages." Furthermore, in 1916 

 W. C. Barton had distributed through the Watson Botanical Exchange Club excellent 

 material from Radnor of both the typical plant and what he correctly named var. 

 longidentata. Even so, Druce persisted in using his epithet and the interesting nature of 

 the variation soon relapsed into the oblivion from which it had emerged. 



Taxonomy 



As reported by Bennett (1917), Gay's type is in the Kew Herbarium, where it is 

 described as follows : " Dentibus calycinis interioribus brevibus, exterioribus longioribus, 

 valde elongatis, filiformibus." The specimens were collected in 1825 near Banyuls-de-mer 

 in Roussillon, close to the Franco-Spanish border, and sent to Gay, who later (1832) 

 published an account of the new variety. Afterwards, he seems to have considered it a 

 distinct species, for he raises to it this rank in his herbarium. 



The synonymy is as follows : — 



P. PORTULA var. LONGIDENTATA Gay, 1832, Notic. sur Endress, 38; 1832, Ann. Sci. Nat., 

 26, 226 ; P. fradini Pomel, 1860, Mater. Fl. Atlant., 156 ; P. portula *[ssp.] longi- 

 dentata (Gay) Boiss. & Reut. ex Nym., 1879, Consp. Fl. Eur., 2, 252 ; P. longidentata 

 (Gay) Batt. 1890, in Batt. & Trab., Fl. Alg., 1, 320 ; P. portula " forme " P. longi- 

 dentata (Gay) Rouy & Camus, 1901, Fl. Fr., 1, 167 ; P. portula proles longidentata 

 (Gay) Rouy, 1927, Consp. Fl. Fr., 107. 



The outer calyx teeth in Gay's type specimens are 1-5-2 mm. long, and this is the 

 extreme reached in various parts of the plant's range. In var. portula the outer teeth 

 are not at all elongated and consequently only attain 0-5 mm. in length at the most. 

 Between these two extremes -the latter always well-marked, the former somewhat less so - 

 every intergradation can be found. The continuity of this variation tends to be obscured by 



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